1. Field of the Invention
Embodiments of the present general inventive concept relate to a method of controlling an image photographing apparatus, which tracks a subject by moving a photographing region.
2. Description of the Related Art
Generally, an image photographing apparatus detects a moving object by a method of using a differential image signal between two frames or a method of using a motion vector. The method of using the differential image signal performs subtraction of pixel values of coordinate points of a previous frame and a current frame, and uses a principle in which a pixel has a value other than “0” if slight motion occurs between the two frames. If pixels have values equal to or greater than a predetermined reference value, it is determined that the pixel values are changed due to appearance of an object or the like and the object is moved. In the method of using the differential image signal, an operation method is simple and motion is rapidly detected.
In contrast, in the method of detecting the moving object using the motion vector, the motion vector between a current frame and a previous frame is detected by a full search method or the like, and it is determined that the object is moved if the motion vector is equal to or greater than a predetermined reference value. The method of detecting the motion of the object using the motion vector is less sensitive to illumination change or noise than the method of using the differential image signal, and the motion direction of the moved object is recognized.
In order to detect the moving object, track the motion of the detected object, and perform photographing using the above-described methods, the image photographing apparatus performs photographing while moving.